The term 'selfish thread' can be replaced by multiple synonyms, depending on the context and the level of severity it implies. Some alternatives include egocentric, self-centered, self-serving, narcissistic, inconsiderate, and thoughtless. When describing someone's behavior, one may use the terms self-absorbed, individualistic, and egotistical. On the other hand, if referring to a conversation or an online discussion that revolves around one person's interests, synonyms like monopolizing, dominating, and one-sided may be suitable. Ultimately, choosing the right synonym depends on the tone, audience, and impact the writer wants to create through their language.